1. Field of the Invention
The present invention relates generally to a converter support device that carries out a recording or reproducing operation with respect to a recording medium while moving relative to the recording medium with a predetermined distance being kept therebetween. The present invention particularly relates to a magnetic head preferably used for magnetic field modulation in magneto-optical recording.
2. Related Background Art
Typical examples of conventional magneto-optical recording magnetic heads include magnetic heads used with respect to mini-disks (hereinafter referred to as MDs). One example of such magnetic heads for MDs is disclosed in JP6(1994)-195851A.
The magneto-optical recording applied to MDs and the like is a kind of perpendicular thermomagnetic recording, in which the recording operation is carried out as follows: a medium is heated partially by a laser beam so that the heated portion of the medium has a decreased coercive force, and a perpendicular magnetic field modulated according to recording signals is applied thereto so that the medium is magnetized and a perpendicular magnetic domain is formed there. This modulated perpendicular magnetic field is generated by a magnetic head. Reproduction is carried out by detecting the rotation of a plane of a reflected polarized light due to the Kerr effect and reading a magnetization direction of each perpendicular magnetic domain.
Data recorded in MDs mainly are music data, but the magneto-optical recording is used also generally for the recording of data and pictures. For the latter purposes, it is necessary to increase a transfer rate by one order of magnitude or more in the case where a MD is used. As a result, recently it is required to increase the frequency of the modulated magnetic field.
The following will describe a magnetic head structure mainly for use with a MD, as a conventional converter support device. FIG. 14A illustrates an overall configuration of this example (see, for example, JP6-195851A). FIG. 14B is a perspective view of a slider mounted on the magnetic head structure shown in FIG. 14A. Further, FIG. 15 is a perspective view illustrating principal parts of a tip of the magnetic head structure shown in FIG. 14A, on which the slider is to be mounted. FIG. 16 is a side cross-sectional view illustrating a state in which the slider is slid on a disk as a recording medium.
In FIG. 14A, 101 denotes a sliding-type slider for use with a MD. Generally, a slider principally functions as a mechanical interface with a recording medium that relatively moves, and in the case where the medium is a MD, a slider is brought into contact with and slid on the medium so as to keep a distance between the converter and the medium.
It should be noted that a slider for fixed magnetic disks keeps a distance between a converter and a medium by levitation due to airflow that is generated by a relative movement with respect to the disk as a recording medium. In many cases of magnetic tapes, flexible disks, etc., a converter itself is brought into contact with the medium, and herein the slider performs a function in expanding a slid area, thereby reducing a contact pressure between the medium and the converter so as to prevent the abrasion of both the medium and the converter.
The slider 101 is made of a resin, and is mounted on a converter composed of a magnetic core 102 and a coil 104 (described later), bonded with the converter so as to enclose it. The magnetic core 102 has an E-shaped cross section and is made of ferrite or the like.
103 denotes a suspension that is composed of a metal elastic body made of a material such as stainless steel, beryllium copper, or phosphor bronze, and the slider 101 is bonded on an end (free end) of the suspension 103.
A spring portion 103a, formed as a part of the suspension 103, generates a force pressing the slider 101 toward a disk 10 side. A gimbal 103b is deformed, thereby causing the slider 101 to change its attitude according to a relative tilt of a surface of the disk 10 and the like.
105 denotes a head base made of a material with high stiffness, for instance, a stainless steel plate. The head base 105 fixes the suspension 103 in the vicinity of the spring portion 103a to facilitate the attachment of the entire magnetic head to a disk device. A protrusion 105a is formed on an end of the head base 105 on the slider 101 side so as to pass with play through an engagement hole 103d provided at the end of the suspension 103 on the slider 101 side. Thus, the protrusion 105a and the engagement hole 103d form a shock-resistant structure such that when a shock with a significant magnitude is applied to the entire magnetic head, the protrusion 105a collides with the periphery of the engagement hole 103d, thereby preventing plastic deformation and damage of the suspension 103.
An example of a slid surface of the slider 101 is disclosed by JP7(1995)-129902A, whose configuration is illustrated in FIG. 14B. On a side of the slider 101 facing the disk 10, a cylindrical-shaped surface 101a is formed as a sliding surface to be brought into contact with the disk 10. 102a denotes a magnetic pole of the magnetic core 102 exposed to the disk side. The cylindrical-shaped surface 101a protrudes on the disk side to a predetermined extent, as compared with the magnetic pole 102a. 
A slidable resin material having excellent abrasion-resistance and some lubricity is applied to the disk-facing surface of the slider 101 including the cylindrical-shaped surface 101a, so as to prevent the abrasion and damage of the slider 101 and the disk 10.
FIG. 15 illustrates principal parts of the tip of the magnetic head structure. A tonguelet 103c is formed on a tip of the suspension 103, to be bonded with the slider 101.
In the case where the slider 101 is brought into contact with and slid with the disk 10 as a recording medium, the spring portion 103a is deformed elastically to apply a predetermined load on the slider 101 in a direction toward the disk 10, which causes the gimbal 103b to be deformed elastically so as to maintain an attitude of the slider 101 relative to the disk 10 while counteracting tilt displacements of the disk 10. Consequently, the magnetic pole 102a is brought into the proximity to a recording film of the disk 10.
FIG. 16 is a cross-sectional view illustrating a state of sliding. The converter composed of the magnetic core 102 and the coil 104 is mounted on the slider 101 as a converter-mounted part so that the converter is enclosed therein. The disk 10 moves in a direction indicated by an arrow A.
In this state, a modulated magnetic field generated by the coil 104 is induced by the magnetic core 102 and is applied via the magnetic pole 102a to the recording film heated by a converged laser beam (not shown). Thus, the thermomagnetic recording is carried out.
However, the foregoing conventional converter support device has the following problems.
For instance, for the speed enhancement such as the improvement of a transfer rate of recorded information with a view toward image recording, it is necessary to increase the modulation frequency of the magnetic field. Furthermore, for the high density of recording in a medium, it is necessary to increase a coercive force of the medium, and for this purpose, it is necessary to increase the strength of the magnetic field. These increase eddy-current loss and hysteresis loss, thereby increasing the power consumption in the converter. Furthermore, the flowing of current (or the recording of information) causes the converter to generate heat due to coil resistances or the like, thereby increasing the power consumption. The power consumed by the converter is turned into heat, thereby raising the temperature of the magnetic core 102 and the coil 104 composing the converter. Since the slider 101 is made of a resin material as a kind of heat insulator, it is difficult to dissipate heat from the electromagnetic transducer enclosed in the resin material. Therefore, slight heat generation causes a great temperature rise.
On the other hand, generally, a magnetic material such as a magnetic core has a Curie temperature, and if the temperature rises above the Curie temperature due to heat generation occurring, for instance, when large current at a high frequency is supplied, the magnetism is lost, which causes impedance to decrease excessively. This causes a large current to flow, thereby further inducing a temperature rise. Finally, this leads to a thermal runaway phenomenon in which burnout of a coil insulation coating and damage of a driving circuit occur. Even if the insulation coating of the coil is not damaged, deterioration of the insulation property or loss of life at high temperature is expected.
Furthermore, though not being described in detail, regarding another converter, for instance, an electrical/optical converter such as a semiconductor laser, it is important to use shorter-wavelength light for high-density recording/reproduction. However, light with a short wavelength has high energy, thereby generating much heat. On the other hand, since in the case of a semiconductor laser, the operation temperature significantly affects life, it is not easy to use the short-wavelength light in a state of being cooled insufficiently.
Thus, in various types of converters, the temperature rise is a significant constraint to the improvement of performances thereof.
Furthermore, in the conventional example, the magnetic core 102 is fixed to the slider 101 by adhesion or the like. Here, a thermal expansion coefficient of the magnetic core 102 and that of the slider 101 are significantly different. Furthermore, since the slider 101 is made of a resin with slidability, it generally has inferior adherability. Therefore, the adhesion is impaired with repetitive thermal expansion and shrinkage over a long period of time, whereby the magnetic core 102 is separated from the slider 101. This makes it impossible to apply a sufficient magnetic field to the recording film, thus leading to a problem in reliability.
Furthermore, when a shock is applied to the magnetic head, an inert force is exerted to, as a point of action, the vicinity of the converter composed of the magnetic core 102 and the coil 104, which has the greatest mass. Since the shock-resistant structure composed of the protrusion 105a and the engagement hole 103d are spaced from the converter to which the inert force is exerted, a significant moment is generated by the inert force, with an engaged portion of the shock-resistant structure functioning as a fulcrum. The moment damages the vicinity of the engagement hole 103d and the gimbal 103b, or causes the protrusion 105a to be disengaged from the engagement hole 103b. 